Helical Gear Shimming

[ThunderCactus]

Your sector and bevel especially need to have a tiny bit of loose, as much as your smallest shim available to you OR LESS.
But the spur needs to be perfect, it's the one absorbing all the torque in the system.
The bevel is taking all the angular force, but a properly height adjusted motor keeps the bevel in it's proper position, the loose is important because of the inherent wobble in the system (your motor isn't 100% secure), helps absorb shocks and prolong motor life.
And if you have a set of good, high accuracy bearings/bushings, the axles stay centered. They break when they wobble.

Anyway, I'll give you an example, prometheus gears on G&P bearings will make it about 5-6 rotations of the sector gear after proper shimming. 8-9 turns with prometheus bearings. Significantly less on bushings, like 3-4 at the very most.
Most importantly, you shouldn't feel them binding anywhere. Some mechboxes are poorly crafted and require some modification to let the gears spin freely.

I shim in this order; spur gear, then sector and bevel at the same time. Once your spur is in there, set your bevel and sector .1-.3mm higher than it so they don't rub. I check the play in the gears by laying the mechbox flat, pushing the gears down, then lifting them up from the back with a small allen key. This gives you a visual on how many shims to add. You should get minimal play (.1mm-.2mm) out of the sector and bevel and pretty well none on the spur.

[turok_t]

Originally Posted by ThunderCactus

Your sector and bevel especially need to have a tiny bit of loose, as much as your smallest shim available to you OR LESS.
But the spur needs to be perfect, it's the one absorbing all the torque in the system.
The bevel is taking all the angular force, but a properly height adjusted motor keeps the bevel in it's proper position, the loose is important because of the inherent wobble in the system (your motor isn't 100% secure), helps absorb shocks and prolong motor life.
And if you have a set of good, high accuracy bearings/bushings, the axles stay centered. They break when they wobble.

Anyway, I'll give you an example, prometheus gears on G&P bearings will make it about 5-6 rotations of the sector gear after proper shimming. 8-9 turns with prometheus bearings. Significantly less on bushings, like 3-4 at the very most.
Most importantly, you shouldn't feel them binding anywhere. Some mechboxes are poorly crafted and require some modification to let the gears spin freely.

I shim in this order; spur gear, then sector and bevel at the same time. Once your spur is in there, set your bevel and sector .1-.3mm higher than it so they don't rub. I check the play in the gears by laying the mechbox flat, pushing the gears down, then lifting them up from the back with a small allen key. This gives you a visual on how many shims to add. You should get minimal play (.1mm-.2mm) out of the sector and bevel and pretty well none on the spur.

ahh!! Thanks for the tip Thundercactus, Im glad im doing something right!